LV10130B - Method of determination of layer thickness - Google Patents

Abstract

Invention allows determining with sufficient preciseness and locality the thickness of a coating - also the thickness of oxide film on metal.The essence of the invention - it is offered to use microhardness as a characteristic feature for the coating, but the thickness of coating t calculated by applying correlation equality t=C x hk, where hk - the critical depth of indentor imprint, which is determined in the breaking point of curve "microhardness - depth of indentor's imprint" and which characterises the condition when the deformation zone under indentor reaches the boundary between coating and base; C- constant, the value of which for the given pair of coating and base materials are determined prior with the help of etalon samples.In compliance with the offered method, a range of microhardness tests are performed on the coated samples, by gradually changing the load. The depth of the indentor's imprint is determined by the size of diagonal imprint. With the obtained data, the curve "microhardness - depth of indentor's imprint" is construed. At the breaking point of the curve, the critical imprint depth hk is determined, but after that with the help of correlation causation - the thickness of the coating.

Description

Method for determination of coating thickness

The present invention relates to non-destructive control techniques, and in particular to non-destructive coating thickness determination techniques.

Non-destructive techniques for determining the thickness of coatings are known and are described in National Standard 13353-79 Non-Destructive Control. Classification of Types and Methods and National Standard 9 * 302-88 Metallic and Non-Metallic Coatings 3 * 1 3 * -6. and 43 * on the sides of Annex I, Table 15. Apparatus implementing these techniques is described in A.M.Valitov, G.I.Silov, Apparatus and control methods for thickness determination in Leningrad, Machine. , 1970. The application of the lined techniques is limited and determines the physical properties of the coatings and substrate; transparency, magnetizability, conductivity, etc. All of these thicknessing techniques require hardware calibration using a large number of benchmarks.

There is not enough localization for known techniques: each measurement requires a surface area of at least 6 mm. They do not allow the thickness of coatings to be determined for layers thinner than 5 mkm, such as oxide layers.

The closest technique to the thickness determination method proposed is the method of determining the micro-hardness of the material by embedding the diamond pyramid at various loads, described in AMG Greenberg et al. ed., M.Metallurgy, 1987,631 pages. According to this technique, the micro-hardness H is determined by the formula H -, where d is the diagonal size of the indentation imprint, P is the applied load. The indenter uses a diamond pyramid (National Standard 9337-31) with a vertex angle I3S ⁰ . The depth h obtained from the compression, corresponding to the shape of the pyramid, is calculated as h = d / 7. The object of the present invention is to provide non-destructive determination of the thickness of thin coatings, regardless of the physical properties of the coating and substrate material, as well as to ensure localization of measurements.

This objective is achieved by taking a series of micro-hardness measurements at different loads for the hardness curve - indentation indentation depth and coating thickness t is determined from the equation t = C h ^, where is the indentation indentation depth corresponding to the curve breakpoint; for a pair of coating and substrate materials, a reference sample of known coating thickness shall be used. The critical indentation depth h, physically describes the state where the deformation zone below the indentor reaches the boundary between the coating and the substrate, and further increasing the indentation depth leads to the involvement of the substrate material in the deformation step.

According to the possible inventions, the coating thickness is determined as follows. For the sample for which the thickness of the coating is to be determined, a series of micro-hardness measurements shall be made, gradually changing the load applied to the indenter. For each load, the hardness of the coating and the depth of indentation shall be determined. Based on the obtained values of hardness and indentation depth, the hardness indenter indentation depth curve is constructed in logarithmic coordinates. The critical indentation depth h ^ corresponds to the break point of the curve. The thickness of the coating is determined from the equation t = G h ^, where is the critical indentation depth, C is the constant determined for a given pair of substrate and coating materials by a reference sample. For this purpose the hardness - indentation indentation curve for the sample of ethanol * is found, the critical depth of indentation is found, and the value of the constant C is found by * XV from the equation G = t / h ^, where t is the thickness of the sample.

The proposed coating thickness determination technique is illustrated by the following graphic images. Fig. I. Remote dependence of micro hardness on inLV 10130 dentor embossing depth for nickel plating on copper substrate. Zim.2 depicts the micro-hardness dependence of the indentation indentation depth on the gold plated covar.

The following examples illustrate the proposed coating thickness determination technique.

Example 1: Determination of thickness of a nickel plating on a copper substrate. System Nickel - Copper Hardness parameters are given in Table I

1st row. A series of micro-hardness measurements are carried out on the coating surface, gradually changing the load. The magnitude of the load applied to the indentor

P (IT) and the corresponding diagonal screen size d (mkm), embossment depth h (mkm) and coating hardness H _,, (GPa) are given in ThaiL. cave in bulb 2. From Table 2, the curve H (h) is constructed in logarithmic coordinates and is plotted in Fig. I. The critical indentation depth of the indentation is defined at the break point of the curve = 10 mkm. For this system, the value of the constant C is C = II, 5 (by tab.I, I.r). Using these data, we obtain a coating thickness of t = C = 115 mkm. According to VS9.302-84, the thickness of the coating determined on the same sample is 110 mkm.

Example 2: Determination of thickness of gold plating on a covar base. The hardness parameters of the gold-covar system are given in the taboo line I S. A series of micro-hardness measurements are carried out on the coating surface, gradually changing the load. Load size P (η) and corresponding indentation diagonal dimension d (mkm), indentation depth, h. (mkm) and coating hardness (GPa) are given in Table 3 · The curve H (h) is plotted in logarithmic coordinates and is plotted in Fig.2. The critical indentation depth of the indentation is 2.0 mkm determined at the break point of the curve. For a given system, the value of constant 0 is C = 2.0 (according to Table 8.8r). Using C values, we obtain a coating thickness t = C hj = 4 _} 0 mkm. Coating thickness determined by VS9.3O284 with cross-section (sanding)

4.

the oar sample has 3.5mkm.

The proposed technique can be applied to any system with different substrate and coating microhardness. Load applied to the indentor

-2 can be changed over a wide range from Ι · ΙΟ to I50K. Using Logarithmic Coordinates Curve Hardness - Depth of indentation indentation for analysis facilitates and refines the determination of the point and magnitude of the curve break, as these coordinates form linear areas of the curve H (h).

Table I gives the values of the micro-hardness and the constant C values determined for the various coating-substrate systems by reference samples. As follows from I.tab.and I.and 2, which characterize the systems with H _p8rkl > H _pam and H _parkl <H _paa respectively, the results of the microc Hardness measurements correspond to the true values of the microcosure of the coating only in the printing depth interval h 4. h ^ . In the imprint, at depths greater than h ^, the substrate material exhibits deformation, as evidenced by the increase in micro-hardness (if Hpā _r kl ^ ^ panP ^{Vaa sa} 'movement (if

The values of the constant C are in the range of 1.5-5.0 for H_ <11 and in the range 5-U for H _{fall; 1} <H _pam .

Using the proposed technique, the microhardness of the coating should be measured over a specified range of embossing depths including h ^. The interval is selected by approximating the values of t and C. Most importantly, at the same time as the thickness of the coating, the true value of the micro-hardness of the coating is determined. Comparison of the results obtained (Example I and 2) The difference between the coating thickness values obtained by the proposed method and the values obtained by direct measurement by means of a sander does not exceed 10% of the actual coating thickness precision for use, especially in batch production.

The proposed technique can also be used in simplified form to perform an ex-control of the coating thickness for a given

Table I

Micro Hardness and Constant C Values for Different Systems Coating - Substrate Based on Reference Samples

No. Cover the urn and base material Hardness of coating, ^H parkl ' ^GPa Substrates hardness, H, GPa pam Anglet H ¹ pam 0 I. nickel copper 5.50 1.35 4.07 H, 5 2. nickel steel 2.35 1.40 2.03 4.8 3. Grace chrome - steel 6.90 2.20 3.13 9.2 4. chrome brass 10.30 1.50 6.90 13.0 £ > * titanium nitride - steel 34.0 4.00 8.50 13.0 6th lead - glass 0.08 6.00 0.01 1.5 7th tin - glass 0.14 6.00 0.02 1.5 3. gold - covar 0.50 1.80 0.36 2.0 9th arsenic sulphide - quartz 0.50 13.0 0.03 1.5

Table 2

Micro-hardness of nickel plating on copper base depending on load and indentation depth

No. Load, Ρ, N Diagonal of pressure, d, mkm Depth of indentation, h, mkm Coat hardness ^H overcoat I. 0.1 5.8 0.82 5.57 2, 0.2 3.1 1.16 5.65 3. 0.3 10.0 1.43 5.56 4. 0.5 13.1 1.90 5.40 5. 1.0 18.3 2.62 5.51 6th 2.0 25.2 3.60 5.34 7th 3.31 33.3 4.76 5.53 8th 5.31 42.3 6.04 5.50 9th 7.31 50.1 7.15 5.40 10th 9.31 55.8 7.97 5.54 II. II, 31 62.4 8.90 5.33 12th 13.31 68.7 9.81 5.23 13th 53.00 180.0 25.7 3.03 14th 100.0 280.0 40.0 2.36 15th 150.0 350.0 50.0 2.27

Table 3

Micro hardness of gold plated us covar substrate depending on load and indentation depth

ITr Load, P, TT Imprint diagonal, d, mkm Indexing depth, h, mkm Coating hardness, Η - -,,, GPa Park ' I. 0.01 4.4 0, S3 0.95 2. 0.02 6.4 0.91 0.90 3. 0.03 7.3 1.12 0.90 4. 0.05 10.1 1.44 0.91 5. 0.07 II, 8 1.68 0.93 6th 0.10 14.1 2.01 0.93 7th 0.20 19.7 2.81 0.95 8th 0.30 23.4 3.34 1.01 9th 0.50 28.2 4.03 1.17 I 0. 1.00 38.8 5.54 1.23

8th

size. In this case, the micro-hardness shall be measured at a load corresponding to the point of refraction of one constant curve, H (h), as determined by the reference sample. The deviation of the obtained hardness numbers from the H-level in the direction of the hardness values is less than that of the reference coat,

The proposed technique allows to determine the thickness of the coating as well as its micro-hardness in the areas of 50 s 50 mkm, i. it has sufficient locality compared to known techniques.

The proposed technique can be used to determine the thickness of the coating on various organic, inorganic and oxide coatings, as well as to determine the thickness of the oxide films. The proposed technique can be used in various industries for non-destructive control of coating thickness.

Cover the urn smith aria

HARDNESS H, GPa

INDENTOR PRINTING DEPTH h, Mkl * 1

Zim.2. Dependence of microhardness on indentation fine art gold plating on covar

HARDNESS H, GPa

INDENTOR PRINTING DEPTH h, MkM

Zim.I. Dependence of Microhardness on Indenter Depth of Depth for Copper

Claims (1)

Formula of the Invention A method for determining the thickness of a coating, comprising determining the functional relationship between the coating properties and its thickness, wherein the microhardness is used to provide a thin coating thickness and the coating thickness t is determined from the equation t = C h, where h, the critical indentation indentation depth determined by the curve hardness - indentation indentation depth at the point of fracture, which describes the 'state where the deformation area below the indenter reaches the boundary between the coating and the substrate and the constant C value for a given coating and substrate pair help.